From DE 41 37 143 A1 has become known a multi-step synchronized countershaft transmission in which each two gears are associated with one of several shifting sets. These shifting sets consist as a rule of sliding sleeves axially movably but non-rotatably situated upon a shaft and which during a shifting operation, interacting with synchronizer rings disposed adjacent to the sliding sleeves, decelerate idler wheels and can non-rotatably connect them with the shaft.
In this known transmission, the two gears (first gear and third gear or second gear and fourth gear), associated with one shifting set, are two gears not consecutively following each other. This transmission construction is associated with the advantage that thereby a transmission shifting system is provided with which an overlapping operation and thus reduced shifting times are possible. But it is a disadvantage that such a transmission cannot be shifting with a selector device having one H-shifting gate since, with such a transmission, only gears immediately following each other can be shifting in the same shifting gate.
From EP 10 34 384 B1 a twelve-gear selector transmission for industrial vehicles is further known in which a splitter group is manually actuated while the main- or rear-mounted group is automatically shifted. For the splitter group and the rear-mounted group, pneumatic shifting devices are provided which, during selection of the shifting gate of the gear desired, are correspondingly activated by means of a manual shifting device. The shift pattern obtained thus corresponds to that of an ordinary six-gear selector transmission. But it is disadvantageous in this construction of transmission that separate pneumatic shifting devices have to be provided in order to make shifting the gears in accustomed manner in an ordinary H- or HH-shift pattern possible.
DE 30 00 577 A1 has, in addition, disclosed a selector device for motor vehicle transmission in which a manual shift lever is shifting in an HH shift pattern. Two shift fingers are disposed upon the selector shaft of the transmission, only one shift finger shifting the four gears of the main transmission. When changing from the second to the third shifting gate, one shift valve is actuated which engages the range change group. When shifting to the third and fourth gears, the second shift finger is then in gear. The separate actuation system of the range change group is also a disadvantage here.
DE 35 27 390 A1 also shows a manually shiftable dual-clutch transmission in which during actuation of the shift lever in a shifting gate, one of the two clutches of the dual-clutch is closed. The disadvantage in this shifting device is the limitation to only four forward gears when the shifting has to be purely manual without external force assistance.
It has finally been described in the not pre-published DE 102 331 547 A1, one shifting device for a transmission where at least one shifting set is associated with two non-consecutive ratio steps of the transmission. This shifting device is equipped with a mechanical conversion device by means of which a manual shifting device with one HH shifting gate can operate such a transmission.
In this shifting device 50, shown in FIG. 3, one shift lever 52 is passed into the HH shifting gate 51 and coupled with two selector shafts 53, 54 in a manner such that a movement of the shift lever 52 to a shifting gate 55 results in a swiveling of the selector shaft 53 around its longitudinal axis. In addition, a first gear wheel 56 which meshes with a second gear wheel 57 upon the second selector shaft 54 is fastened upon the first selector shaft 53. When the first selector shaft 53 rotates, the second selector shaft 54 rotates in the opposite direction. When selecting the shifting gate by the shift lever 52 in one selector gate 58, the two selector shafts 53, 54 are moved coupled by force parallel with their longitudinal axes.
The two selector shafts 53, 54 have besides shift fingers 59, 60, 61 which, according to the gear introduced, engage in recesses 62, 63 individual for each gear of shift rods 64 which are connected with shift forks. The shift forks for their part are in communication with the sliding sleeves of the shifting sets which, during an operation for non-rotatable connection of idler wheels with their shaft, are axially moved on these.
Against this background, the problem to be solved by the invention is to introduce the structure of a motor vehicle transmission in which each two gears situated in a shifting gate of an H- or multi-H-shifting gate of a transmission can be actuated by two different shifting sets or coupling devices shiftable by means of a conversion device known from DE 102 31 547 A1. The novel transmission structure must furthermore be utilizable for a six-gear transmission and for a seven-gear transmission to make thus possible to obtain a specially small length.